This invention relates to a hinge mechanism. More particularly, this invention relates to a hinge mechanism for hinging a cover to a housing. The cover can be tilted between a closed and an open position in relation to the housing. In the open position, the cover is securely held in place.
In the prior art, a cover for a device such as a palm-sized personal computer (P/PC) or personal digital assistant (PDA) is generally attached to a housing of the device using a simple pin and socket hinge. In such a device, the cover has a panel for either partially or fully covering a surface of the housing to protect a display on the surface or to protect the device against inadvertent activation. The panel of the cover has two pins arranged along a pivoting axis. These pins are usually round in cross section. Corresponding to these pins on the cover are apertures on the housing. When assembled, the pins on the cover are fitted into these corresponding apertures in the housing. Such an assembly allows the cover to be hinged to and tilted about the housing. The cover tilts about the pivoting axis of the pins to an open and a closed position.
In the closed position, the panel is juxtaposed to a housing surface to cover the surface. In the open position, the cover is tilted away from the surface to allow access to control buttons and the display. The cover is normally held in the open position by a simple detent on the device. This detent includes a bump of the cover and a corresponding dimple on the housing. In the open position, the bump sits snugly in the dimple to prevent the cover from tilting back to the closed position.
Such a hinge mechanism including the bump and dimple works but is prone to wear. Through frequent use, the bump on the cover wears down and does not engage well with the dimple to hold the cover in place. Such poor engagement will result in the cover being easily dislodged when in the open position. The cover will then have the tendency to tilt back towards the closed position when the device is subjected to rough use.
From the foregoing, the prior art therefore has a need for a low-cost and longer lasting hinge mechanism that is able to continue to function after prolonged usage. This hinge should also allow the hinged parts to be held apart in an open position substantially securely to prevent the two parts from being easily dislodged from the open position. This hinge should also preferably provide a user with a tactile feel that the open position is reached when tilting one part about the other.
In accordance with a preferred embodiment, a hinge mechanism suitable for hinging a first part of a device to a second part of the device has a pair of pins attached to the first part and a pair of guides on the second part. The pair of guides receives the pins to allow the first part to hinge to the second part. The first part can be tilted from a closed position to an open position in relation to the second part. Each guide defines a first guide portion and a second guide portion within the confines of the guide. A pivoting point is provided on either the first or the second part of the device. A corresponding cam-profiled section is provided on the other part for interacting with the pivoting point to urge the pin into the corresponding second guide portion for securing the first part in the open position when the first part is tilted from the closed position to the open position.
Preferably, the cam-profiled section includes a notch that latches onto the pivoting point to prevent the parts from being dislodged when in the open position.
Also, preferably each pin has a flattened cross-section that has a narrow and a wide dimension. The second guide portion is also constricted to receive the pin by the narrow dimension so that the pin is securely held in the second guide portion when the first part is in the open position.
Preferably, the hinge mechanism further includes at least one bump along the periphery within the confines of the guide between the first and the second portions of the guide. This bump restricts the movement of the pin between the first guide portion and the second guide portion.